1. Field of the Invention
This invention relates to a paper shredder, particularly to a lubricating pack specifically designed for paper shredders so as to provide lubrication between cutting blades of the paper shredder upon direct contact with the lubricant, thereby extending the lifespan of the paper shredder.
2. Background
It is widely known that paper shredders for shredding incorporate plural cutting blades and spacers passing through rotary shafts that are driven to rotate towards each other by a motor and gear box so as to shred paper passing through the rotary shafts into strips by shear forces. Shredders can be classed into two types, the strip-cut shredders and crosscut shredders, according to the machine cutting style. The former shredders arrange cutting blades to the rotating cutter shafts in a manner for cutting the paper in a longitudinal direction to form strips. The later shredders include blades that include more than one cutting edge part, and each cutter is disposed helically along the rotary cutter shaft for first cutting paper along a horizontal direction into strips and then cutting paper along a longitudinal direction into paper chips.
Regardless of being strip-cut or crosscut shredders, the extended metal-to-metal contact and the high temperature generated in cutting paper due to concentrated stress that the cutting blades experience would dramatically reduce the cutting efficiency and shorten the lifespan of the paper shredders. Experiences prove that periodic lubrication and maintenance to the cutting blades can effectively resolve the afore-mentioned drawbacks.
U.S. Pat. No. 5,491,229 discloses a paper shredder with an improved lubrication system and method of lubricating; U.S. Pat. No. 5,186,398 discloses method and apparatus for lubricating the cutting elements of a shredding machine. Both patents intend to extend the lifespan of the paper shredder by providing lubrication to the cutting blades of the paper shredder. However, a closer look of the two patents reveals that, though they are able to serve the purpose of lubricating the cutting blades, the complicated constructions not only increase the manufacturing cost of the paper shredders, but also reduce the likelihood of commercializing the inventions. For example, the use of timers, oil pumps and manifolds all require additional peripheral devices that significantly increase the manufacturing cost. In addition, the use of oil drip to provide lubrication to the cutting blades requires precise control of oil drip amount and rate as well as lubrication uniformity, or resulting in insufficient lubrication or even fire hazards due to excessive oil drip.